Headers for resource tracking.

chrome/browser/loader/resource_tracker_observer.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_LOADER_RESOURCE_TRACKER_OBSERVER_H_
+#define CHROME_BROWSER_LOADER_RESOURCE_TRACKER_OBSERVER_H_
+
+#include <stdint.h>
+
+// This interface is used by clients who want to be notified when a resource is
+// requested or completes loading, and to report the size of the resource.
+class ResourceTrackerObserver {

[Dmitry Titov, 2017/06/14 19:56:37]

Naming: This is an observer of resource loading. Maybe
offline_pages::ResourceLoadingObserver?

[Dmitry Titov, 2017/06/14 19:56:37]

Since this is going to be used by OfflinePages, should it live in c/o_p/core or
crome/b/o_p?

[Pete Williamson, 2017/06/15 01:03:27]

Done.

[Pete Williamson, 2017/06/15 01:03:27]

Done.

+ public:
+  enum ResourceDataType {
+    APPLICATION,
+    MEDIA,
+    EXAMPLE,
+    IMAGE,
+    MESSAGE,
+    MODEL,

[Dmitry Titov, 2017/06/14 19:56:37]

Similarly, lets just have the types we are going to process in immediate future.
I guess it's TEXT_CSS and IMAGE?

[Pete Williamson, 2017/06/15 01:03:27]

Done.

+    MULTIPART,
+    TEXT_CSS,
+    TEXT_HTML,
+    TEXT_PLAIN,
+    TEXT_SCRIPT,
+    XHR,
+    OTHER,
+    RESOURCE_DATA_TYPE_COUNT,
+  };
+
+  // Report when a resource starts or completes loading.
+  virtual void ObserveResourceTracking(ResourceDataType type, bool started) = 0;
+
+  // Report how many bytes were received for a resource.
+  virtual void OnNetworkBytesChanged(int64_t received_bytes) = 0;
+};
+
+#endif  // CHROME_BROWSER_LOADER_RESOURCE_TRACKER_OBSERVER_H_